Tubulopapillary Carcinoma-A Frequent Over-Diagnosed Entity in Canine Mammary Gland Tumors

Abstract

Tubulopapillary carcinoma is reported to have the best prognosis among the entity of simple carcinoma in canine mammary gland tumors. Immunohistochemical stain for p63 and calponin, described as myoepithelial cell markers, are helpful in determining the invasiveness of human breast tumors. Nineteen canine cases with original diagnosis of tubulopapillary carcinoma were selected for study of p63 and calponin. Ten of the selected 19 cases showed preserved myoepithelial cells highlighted by p63 and calponin staining surrounding the tumor cells and none of them developed recurrence or metastasis. The remaining 9 cases revealed loss of myoepithelial cells by negative staining for p63 and calponin and five of them developed metastasis or tumor-related death. The time of initial presence of clinical symptoms to pathological diagnosis and the survival time were also statistically lesser in the 9 cases without expression of p63 and calponin (Ρ= 0.001 and Ρ= 0.021, respectively). In conclusion, tubulopapillary carcinoma may be an over-diagnosed entity in canine mammary tumors. Immunohistochemical stain for p63 and calponin is recommended for difficult cases to determine the malignancy in canine mammary tubulopapillary tumors.